The active site sections of the metalloproteins hemerythrin, hemocyanine, and azurine will be synthesized by attaching the appropriate numbers of imidazoles, thiol groups, and/or thioether groups to bicyclic organic compounds so that all the metal liganding groups are held, by the organic structure, in the same relative positions they occupy in natural systems. This will be accomplished by various metal-catalyzed coupling reactions, Diels-Alder reactions, and imidazole ring syntheses. New synthetic methodology will be developed for coupling and Diels- Alder reactions involving imidazoles and other heterocycles. The biomimetic behavior of the metal complexes of the synthetic site molecules will be studied by fast kinetic and various spectroscopic methods. The application of these synthetic procedures to the preparation of a variety of other multi-imidazoles containing active sites will also be explored.